High level of sugar in blood is known to have dangerous consequences on health. But, for the first time researchers at the University of Leicester have demonstrated the process of how high level of sugar in blood can affect the contraction of blood vessels, resulting in potentially dangerous effects on the heart and blood pressure.
Dr. Richard Rainbow who leads the team of researchers from the University’s Department of Cardiovascular Sciences said that when the glucose levels are raised, the blood vessels contract more strongly than they do at ‘normal physiological’ levels.
The contraction and relaxation of blood vessels occur in order to control blood pressure. High blood pressure signifies that the blood vessels are more contracted. The team of researchers made use of electrophysiology and myography techniques to examine the impact of glucose on arterial myocytes – the cells that make up the tissue of our blood vessels, and have identified a mechanism that controls the narrowing of blood vessels.
The reason why heart attacks occur is blocked arteries – these arteries are bestowed with the task of providing blood to the heart to fulfill its nutrient and oxygen needs. In case the level of glucose in blood at the time of a heart attack is high, it could make this block more severe by causing the blood vessel to contract more, leading to a higher risk of complications.
Dr. Richard Rainbow who is also a Lecturer in Cardiovascular Cell Physiology opined that their study have shown that the amount of sugar in the blood changes the behaviour of blood vessels making them contract more than normal. This could result in higher blood pressure, or could reduce the amount of blood that flows through vital organs. He further added that as this was an experimental lab study, we can draw conclusions about cause and effect in a controlled environment. A known signalling protein family, protein kinase C has been identified as a key part of this enhanced contractile response. Through this study, it has also been showed that the normal level of contractile response can be restored, and the effects on the heart can be reversed with inhibitors of these proteins.
This study is the first of its kind that shows direct evidence of blood vessel contraction to glucose, and the potential mechanism behind this contractile response. Many people who suffer a heart attack have high glucose due to the ‘stress response’, which means that even people who are not diabetic may become hyperglycaemic during a heart attack.
The research team working on this study has previously investigated the effects of glucose on the cardiovascular system, diabetes and heart function. Their previous researches have revealed that high glucose from any cause, not just diabetes, was an indicator of a ‘worse outcome’ following a heart attack. One of their research showed that glucose interferes with the normal function of the heart, like arrhythmia and abolishing the built-in protective mechanisms that the heart can activate on stress.
Dr. Rainbow opined that the findings of the study are significant as it shows that glucose has an important physiological effect on the normal functioning of the cardiovascular system. If such a condition is left untreated for long, results could be life-threatening if left untreated. He added that their data show a clear glucose-induced potentiation of contraction in blood vessels. One way to tackle it is to target the specific types of protein kinase C that are shown to be involved in this. It can provide a novel therapeutic route for improving outcome in ischaemic diseases, such as heart attack or stroke.
Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation, said that by targeting PKC to block blood vessel constriction caused by high levels of glucose in the blood, improved treatments can be devised for patients whose recovery from heart attack is complicated by raised glucose levels.
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